U.S. patent number 7,523,615 [Application Number 11/093,640] was granted by the patent office on 2009-04-28 for telemetry system.
This patent grant is currently assigned to General Electric Company. Invention is credited to Malcolm John Ashby, Anant Pal Singh, Terry Eugene Viel.
United States Patent |
7,523,615 |
Singh , et al. |
April 28, 2009 |
Telemetry system
Abstract
A method for predicting bearing failure of a differential
bearing including an inner race, an outer race, and a plurality of
rolling elements positioned between the inner and outer race, the
method includes coupling a measuring apparatus comprising at least
one of a strain gage and an accelerometer to the differential
bearing, coupling a cable to the measuring apparatus, wherein the
cable is adapted for passage through a rotating component, and
coupling a transmitter to the cable, wherein the transmitter is
configured to transmit a plurality of signals from the measuring
apparatus to a remote location to facilitate predicting a failure
of the differential bearing.
Inventors: |
Singh; Anant Pal (Cincinnati,
OH), Viel; Terry Eugene (Hamilton, OH), Ashby; Malcolm
John (Hamilton, OH) |
Assignee: |
General Electric Company
(Schenectady, NY)
|
Family
ID: |
36060856 |
Appl.
No.: |
11/093,640 |
Filed: |
March 30, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060218927 A1 |
Oct 5, 2006 |
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Current U.S.
Class: |
60/772;
340/870.07; 702/33; 73/593; 384/448; 324/207.25 |
Current CPC
Class: |
F16C
19/527 (20130101); F16C 41/008 (20130101); F01D
17/02 (20130101); F01D 25/162 (20130101); F16C
19/52 (20130101); F16C 19/26 (20130101); F16C
27/04 (20130101); F16C 19/55 (20130101); F16C
2233/00 (20130101); F16C 2360/23 (20130101) |
Current International
Class: |
F02C
1/00 (20060101) |
Field of
Search: |
;340/870.07,682
;73/862.322,593,660 ;324/207.19,207.25,207.62 ;356/32-35.5
;702/33-36,40-43,182-185,188,56,141,113,122,179,181 ;384/448
;60/772 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2062875 |
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May 1981 |
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GB |
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02155893 |
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Jun 1990 |
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JP |
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Primary Examiner: Rodriguez; William H
Attorney, Agent or Firm: Andes, Esq.; William Scott
Armstrong Teasdale LLP
Government Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
The U.S. Government may have certain rights in this invention
pursuant to contract number NAS3-01135 Task Order 23.
Claims
What is claimed is:
1. A method for predicting bearing failure of a differential
bearing including an inner race, an outer race, and a plurality of
rolling elements positioned between the inner and outer race, said
method comprising: coupling the differential bearing between a
first turbine shaft and a second turbine shaft; coupling a
measuring apparatus comprising at least one of a strain gage and an
accelerometer to the differential bearing; coupling a cable to the
measuring apparatus, wherein the cable is adapted for passage
through a rotating component; and coupling a transmitter to the
cable, wherein the transmitter is configured to transmit a
plurality of signals from the measuring apparatus to a remote
location to facilitate predicting a failure of the differential
bearing.
2. A method in accordance with claim 1 further comprising coupling
the transmitter to a telemetry module, wherein the telemetry module
is configured to supply power to the transmitter and to the
measuring apparatus.
3. A method in accordance with claim 2 wherein the telemetry module
includes a first pair of coils and a second pair of coils, said
method further comprising: generating power utilizing the first
pair of coils; channeling the power to the telemetry module and the
measuring apparatus; and transmitting the plurality of signals from
the telemetry module to a first antenna that is fixedly coupled to
a stationary surface of a gas turbine engine utilizing the second
pair of coils.
4. A method in accordance with claim 3 wherein the first and second
pairs of coils each include a stationary coil and a rotating coil,
said method further comprising: generating power utilizing the
first pair of coils; channeling the power to the telemetry module
and the measuring apparatus; and transmitting the plurality of
signals from the telemetry module to a first antenna that is
fixedly coupled to a stationary surface of a gas turbine engine
utilizing the second pair of coils.
5. A method in accordance with claim 3 further comprising coupling
the telemetry module to a gas turbine engine such that the
telemetry module is configured to rotate with the differential
bearing.
6. A method in accordance with claim 3 further comprising
transmitting signals from the first antenna to a second antenna
that is positioned remotely from a gas turbine engine, wherein the
second antenna is operationally coupled to a bearing monitoring
system that is configured to receive the signals from the second
antenna, and utilize the received signals to facilitate predicting
a failure of the differential bearing.
7. A telemetry system that is configured to predict a bearing
failure of a differential bearing including an inner race, an outer
race, and a plurality of rolling elements positioned between the
inner and outer race, said telemetry system comprises: a measuring
apparatus comprising at least one of a strain gage and an
accelerometer coupled to said differential bearing; a cable
connected at one end to said measuring apparatus adapted for
passage through a rotating component; and a transmitter coupled to
said cable and configured to transmit a plurality of signals from
said measuring apparatus to a remote location to facilitate
predicting a failure of the differential bearing; wherein said
differential bearing is coupled between a first turbine shaft and a
second turbine shaft.
8. A telemetry system in accordance with claim 7 wherein said
transmitter is electrically coupled to a telemetry module, said
telemetry module is configured to supply power to said transmitter
and to said measuring apparatus.
9. A telemetry system in accordance wit claim 8 further comprising:
a first pair of coils configured to generate power utilized by said
telemetry module and said measuring apparatus; and a second pair of
coils configured to transmit said plurality of signals from said
telemetry module to a first antenna that is fixedly coupled to a
stationary surface of a gas turbine engine.
10. A telemetry system in accordance with claim 9 wherein said
first and second pairs of coils each comprise a stationary coil and
a rotating coil.
11. A telemetry system in accordance with claim 9 wherein said
telemetry module is configured to rotate with said differential
bearing.
12. A telemetry system in accordance with claim 9 wherein said
first antenna is configured to transmit signals to a second antenna
that is positioned remotely from the gas turbine engine, said
second antenna operation coupled to a bearing monitoring system
that is configured to receive the signals from the second antenna,
and utilize the received signals to facilitate predicting a failure
of said differential bearing.
13. A gas turbine engine assembly comprising: a core gas turbine
engine comprising: a first rotor shaft; a second rotor shaft; a
differential bearing coupled between said first and second rotor
shafts, said differential bearing comprising an inner race, an
outer race, and a plurality of rolling elements positioned between
the inner and outer race; a measuring apparatus comprising at least
one of a strain gage and an accelerometer coupled to said
differential bearing; and a telemetry system that is configured to
predict a bearing failure of said differential bearing, said
telemetry system comprising: a cable connected at one end to said
measuring apparatus adapted for passage through a rotating
component; and a transmitter coupled to said cable and configured
to transmit a plurality of signals from said measuring apparatus to
a remote location to facilitate predicting a failure of the
differential bearing.
14. A gas turbine engine assembly in accordance with claim 13
wherein said transmitter is electrically coupled to a telemetry
module, said telemetry module is configured to supply power to said
transmitter and to said measuring apparatus.
15. A gas turbine engine assembly in accordance with claim 14
further comprising: a first pair of coils configured to generate
power utilized by said telemetry module and said measuring
apparatus; and a second pair of coils configured to transmit said
plurality of signals from said telemetry module to a first antenna
that is fixedly coupled to a stationary surface of said gas turbine
engine.
16. A gas turbine engine assembly in accordance with claim 15
wherein said first and second pairs of coils each comprise a
stationary coil and a rotating coil.
17. A gas turbine engine assembly in accordance with claim 15
wherein said telemetry module is configured to rotate with said
differential bearing.
18. A gas turbine engine assembly in accordance with claim 15
wherein said first antenna is configured to transmit signals to a
second antenna that is positioned remotely from the gas turbine
engine, said second antenna operation coupled to a bearing
monitoring system that is configured to receive the signals from
the second antenna, and utilize the received signals to facilitate
predicting a failure of said differential bearing.
Description
BACKGROUND OF THE INVENTION
This application relates generally to gas turbine engines, and more
particularly, to a bearing assembly used within a gas turbine
engine and a method of monitoring same.
Gas turbine engines typically include a fan assembly, a core engine
including a compressor, a combustor, and a first turbine, i.e.
high-pressure turbine, and a second or low-pressure turbine that is
coupled axially aft of the core gas turbine engine. The fan
assembly and the low pressure turbine are coupled together using a
first shaft, and the compressor and the high-pressure turbine are
coupled together using a second shaft. At least one known gas
turbine engine also include a differential bearing, i.e.
inter-shaft bearing, that is coupled between the first and second
shafts, respectively.
During operation, failure of a bearing assembly may result in an In
Flight Shut Down (IFSD), and/or an Unscheduled Engine Removal
(UER). Therefore, at least one known gas turbine engine includes a
magnetic chip detection system that includes a magnet that attracts
metallic debris that is created during bearing contact fatigue
failures such as, but not limited to micro-spalling, peeling,
skidding, indentations, and/or smearing. More specifically,
magnetic chip detectors facilitate identifying the presence and
quantity of metallic debris in a gas turbine lube oil scavenge
line. In addition, a scanning electron microscope (SEM) may be used
to determine the source of the metallic debris. However, known
magnetic chip detection systems and SEM analysis systems can only
detect a bearing spalling that has already occurred.
At least one known gas turbine engine also includes a vibration
measurement system that transmits relatively high frequency
acoustic emissions through the bearing to verify a bearing failure
caused by bearing contact fatigue that has previously occurred.
However, known vibration measurement systems may not be able to
successfully identify the bearing failure if the transmitted signal
is degraded when passed through a lubricant film that is used to
lubricate the bearing. Therefore, identifying the bearing component
frequencies among a plurality of engine operating frequencies may
be relatively difficult. Accordingly, known systems are generally
not effective in detecting initial bearing flaws and/or defects
that may result in bearing spalling, in monitoring bearing damage
and/or spall propagation, or in assessing the overall bearing
damage including multi-spall initiations and progression.
BRIEF DESCRIPTION OF THE INVENTION
In one aspect, a method for predicting bearing failure of a
differential bearing including an inner race, an outer race, and a
plurality of rolling elements positioned between the inner and
outer race is provided. The method includes coupling a measuring
apparatus comprising at least one of a strain gage and an
accelerometer to the differential bearing, coupling a cable to the
measuring apparatus, wherein the cable is adapted for passage
through a rotating component, and coupling a transmitter to the
cable, wherein the transmitter is configured to transmit a
plurality of signals from the measuring apparatus to a remote
location to facilitate predicting a failure of the differential
bearing.
In another aspect, a telemetry system that is configured to predict
a bearing failure of a differential bearing including an inner
race, an outer race, and a plurality of rolling elements positioned
between the inner and outer race is provided. The telemetry system
includes a measuring apparatus comprising at least one of a strain
gage and an accelerometer coupled to the differential bearing, a
cable connected at one end to the measuring apparatus adapted for
passage through a rotating component, and a transmitter coupled to
the cable and configured to transmit a plurality of signals from
the measuring apparatus to a remote location to facilitate
predicting a failure of the differential bearing.
In a further aspect, a gas turbine engine assembly is provided. The
gas turbine engine assembly includes a core gas turbine engine
including a first rotor shaft, a second rotor shaft, a differential
bearing coupled between the first and second rotor shafts, the
differential bearing comprising an inner race, an outer race, and a
plurality of rolling elements positioned between the inner and
outer race, a measuring apparatus comprising at least one of a
strain gage and an accelerometer coupled to the differential
bearing, and a telemetry system that is configured to predict a
bearing failure of the differential bearing. The telemetry system
includes a cable connected at one end to the measuring apparatus
adapted for passage through a rotating component, and a transmitter
coupled to the cable and configured to transmit a plurality of
signals from the measuring apparatus to a remote location to
facilitate predicting a failure of the differential bearing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is schematic illustration of an exemplary gas turbine engine
assembly;
FIG. 2 is a cross-sectional view of an exemplary differential
bearing assembly that may be used in the gas turbine engine shown
in FIG. 1;
FIG. 3 is a cross-sectional view of an exemplary outer race that
may be used with the differential bearing assembly shown in FIG.
2;
FIG. 4 is a perspective view of the outer race shown in FIG. 2;
FIG. 5 is cross-sectional view of a portion of the exemplary gas
turbine shown in FIG. 1 that includes an exemplary telemetry system
in a first operational configuration;
FIG. 6 is cross-sectional view of a portion of the exemplary gas
turbine shown in FIG. 1 that includes the exemplary telemetry
system in a second operational configuration; and
FIG. 7 is a bearing monitoring system that may be used to monitor
the differential bearing assemblies shown in FIGS. 2 and 3.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic illustration of an exemplary gas turbine
assembly 9 that includes a core gas turbine engine 10 including a
fan assembly 12, a high pressure compressor 14, and a combustor 16.
In the exemplary embodiment, gas turbine engine 10 is a military
gas turbine engine that is available from General Electric Company,
Cincinnati, Ohio. Gas turbine engine 10 also includes a high
pressure turbine 18 and a low pressure turbine 20. Fan assembly 12
and turbine 20 are coupled by a first shaft 24, and compressor 14
and turbine 18 are coupled by a second shaft 26. First shaft 24 is
coaxially positioned within second shaft 26 about a longitudinal
centerline axis 28 of engine 10.
In operation, air flows through fan assembly 12 and compressed air
is supplied from fan assembly 12 to high pressure compressor 14.
The highly compressed air is delivered to combustor 16. Airflow
from combustor 16 drives rotating turbines 18 and 20 and exits gas
turbine engine 10 through an exhaust system (not shown).
FIG. 2 is a cross-sectional view of an exemplary embodiment of a
differential bearing assembly 50 that may be used with a gas
turbine engine, such as engine 10 shown in FIG. 1. In the exemplary
embodiment, differential bearing assembly 50 is coupled between
first shaft 24 and second shaft 26. Although, the invention
described herein is with respect to a single differential bearing
50, it should be realized that the invention described herein may
also be utilized with a gas turbine engine that includes a
plurality of differential bearings 50. Moreover, the invention
described herein may also be utilized with a plurality of roller
and/or ball bearing assemblies within gas turbine engine 10.
Differential bearing assembly 50 includes a rotating inner race 52
secured to shaft 26 that extends between high pressure turbine 18
and high pressure compressor 14. Differential bearing assembly 50
also includes a rotating outer race 54 that is secured to shaft 24
that extends between low pressure turbine 20 and fan assembly 12,
and a plurality of bearings 56, i.e. rolling elements, that are
positioned between inner and outer races 52 and 54 respectively. In
the exemplary embodiment, bearings 56 are roller bearings. In an
alternative embodiment, bearings 56 are ball bearings.
In the exemplary embodiment, (shown in FIG. 2) outer race 54
includes a first portion 60 that is substantially L-shaped, a
second portion 62 that is substantially L-shaped, and at least one
measuring device 70 that is coupled to first portion 60. In the
exemplary embodiment, measuring device 70 is positioned between
first and second portions 60 and 62. More specifically, measuring
device 70 is coupled to first portion 60, and second portion 62 is
coupled circumferentially around an exterior surface of both
measuring device 70 and first portion 60 to facilitate protecting
measuring device 70 from damage. In the exemplary embodiment, both
first and second portions 60 and 62 are coupled to shaft 24 using a
plurality of fasteners 66, and are therefore configured to rotate
with shaft 24.
In another exemplary embodiment (shown in FIG. 3), outer race 54
includes first portion 60 and second portion 62 that is
substantially L-shaped, and at least one measuring device 70 that
is coupled to first portion 60. In the exemplary embodiment,
measuring device 70 is positioned between first and second portions
60 and 62. More specifically, measuring device 70 is coupled to
first portion 60 and second portion 62 is coupled radially around
an exterior surface of both measuring device 70 and first portion
60 to facilitate protecting measuring device 70 from damage. In the
exemplary embodiment, first portion 60 is coupled to second portion
62 using a plurality of fasteners 68, and second portion 62 is
coupled to shaft 24 using a plurality of fasteners 66. Accordingly,
and in the exemplary embodiment, first and second portions 60 and
62, and measuring device 70 are all configured to rotate with shaft
24.
FIG. 4 is a perspective view of outer race 54 (shown in FIGS. 2 and
3) that includes measuring device 70. Measuring device 70 is
coupled to outer race 54 and is therefore configured to rotate with
outer race 54. In one exemplary embodiment, measuring device 70 is
a wire strain gage 72 that is configured to transmit a signal
indicative of the reaction forces within bearing assembly 50 to an
external monitoring system (not shown) for further analysis. Strain
gage as used herein is defined as a resistive elastic unit whose
change in resistance is a function of applied strain in accordance
with Equation 1:
.times..times. ##EQU00001##
wherein S is the strain sensitivity factor of the gage material, R
is the resistance, and .epsilon. is the strain. In the exemplary
embodiment, wire strain gage 72 includes at least one resistor 74,
such as, but not limited to a metal foil, that is bonded to a
respective elastic backing 76, which is then bonded to an exterior
surface 78 of outer race 54. In use, the resistance of the wire,
i.e. resistor 74, increases with increasing strain and decreases
with decreasing strain as shown in Equation 2:
.rho..times..times..times..times. ##EQU00002##
wherein R is the total resistance, .rho. is resistivity, l is the
length of the wire, and A is the cross-sectional area of the wire.
Accordingly, the resistance change R is a combination effect of
changes in length, cross-sectional area, and resistivity of wire
74. In an alternative embodiment, strain gage 72 is a semiconductor
strain gage, for example. During operation, strain gage 72 is
therefore configured to convert mechanical motion into an
electronic signal, such that a change in capacitance, inductance,
and/or resistance is proportional to the strain experienced by
strain gage 72. For example, when wire 74 is held under tension, it
gets slightly longer and its cross-sectional area is reduced. This
changes its resistance (R) in proportion to the strain sensitivity
(S) of wire 74 resistance. When a strain is introduced, the strain
sensitivity, which is also called the gage factor therefore
increases.
Strain gage 72 is suitably configured to measure a particular type
of strain, or combinations of strains in more than one direction.
For example, a strain gage that includes a single element foil is
used to measure the strain of an element in a known direction, a
double element foil is used to measure the strain in two known
directions, a three element rosette is used to measure biaxial
strain in unknown directions, a four element, full bridge element
is used to measure tangential and radial strain, etc.
In the exemplary embodiment, strain gages 72 are coupled to outer
race exterior surface 78 such that strain gage 72 is a surface
mounted strain gage 72. In an alternative embodiment, strain gage
72 is embedded at least partially within outer race 54. In the
exemplary embodiment, a single strain gage 72 is coupled to outer
race 54 to facilitate predicting a failure of bearing assembly 50.
In an alternative embodiment, a plurality of strain gages 72 are
coupled to outer race 54 to facilitate predicting a failure of
bearing assembly 50.
In the exemplary embodiment, measuring device 70 also includes at
least one accelerometer 73 that is configured to transmit a signal
indicative of acceleration and/or velocity of outer race 54. More
specifically, accelerometer 73 monitors changes in acceleration,
i.e. the rate of change of velocity with respect to time, of outer
race 54, and communicates these changes to a bearing monitoring
system.
Accelerometer 73 is suitably configured to measure acceleration and
may include at least one of a piezo-film accelerometer, surface
micro-machined capacitive (MEMS) accelerometer, a bulk
micro-machined capacitive accelerometer, a piezo-electric
accelerometer, a magnetic induction accelerometer, and/or an
optical accelerometer, for example.
In the exemplary embodiment, accelerometer 73 is coupled to outer
race exterior surface 78 and extends at least partially through
outer race 54 such that accelerometer 73 rotates with outer race
54. In one embodiment, bearing assembly 50 includes at least one
accelerometer 73. In the exemplary embodiment, bearing assembly 50
includes two accelerometers 73. In an alternative embodiment,
bearing assembly 50 includes more than two accelerometers 73 that
are each coupled to outer race 54 and therefore configured to
rotate with outer race 54.
Outer race 54 also includes a mounting flange 80 that is configured
to couple outer race 54 to gas turbine engine 10. Specifically,
mounting flange 80 includes a plurality of openings 79 that are
sized to receive a fastener 66 to facilitate coupling outer race 54
to shaft 24. In the exemplary embodiment, outer race 54 and flange
80 are formed together unitarily.
Bearing assembly 50 also includes a wiring harness 82 to facilitate
electrically coupling strain gages 72 and/or accelerometers 73 to a
bearing monitoring system such as bearing monitoring system 200
(shown in FIG. 7). Wiring harness 82 is coupled to a transmitter
(shown in FIGS. 5 and 6) that is configured to transmit a signal
such as, but not limited to, an RF signal, to bearing monitoring
system 200. During assembly, a wiring harness first end 84 is
coupled to each respective strain gage 72 and accelerometer 73, and
a wiring harness second end 86 is channeled through at least one
opening 79 and into a bearing cavity 81 to facilitate transmitting
a signal such as, but not limited to, an RF signal, from each
respective strain gage 72 and/or accelerometer 73 to a remote
bearing monitoring system 200.
In the exemplary embodiment, gas turbine assembly 9 also includes a
telemetry system 90. As used herein the term telemetry system is
defined as an electrical apparatus for measuring a quantity such as
pressure, speed, acceleration and/or temperature, for example of
bearing assembly 50, and transmitting the result to a distant
location. In the exemplary embodiment, as shown in FIG. 5,
telemetry system 90 includes a rotating transmitter 92 that is
electrically coupled to at least one of strain gages 72 and/or
accelerometers 73 via wiring harness 82. In the exemplary
embodiment, transmitter 92 is configured to transmit an RF signal,
for example, to a rotating telemetry module 94. Telemetry module 94
is therefore configured to rotate with bearing assembly 50. In the
exemplary embodiment, telemetry module 94 is configured to supply
power to transmitter 92 via a wiring harness 96, to transmit power
to strain gages 72 and/or accelerometers 73 via wiring harness 82,
and to transmit a signal received from transmitter 92 to a
stationary antenna 98.
Accordingly, and in the exemplary embodiment, telemetry system 90
includes a first pair of induction power coils 100 that include a
stationary coil 102 and a rotating coil 104 that is coupled
radially inwardly of stationary coil 102 that facilitate generating
power for transmitter 92, and telemetry module 94, and thus
facilitates the real-time collection of data from bearing assembly
50. Telemetry system 90 also includes a second pair of induction
coils 110 that include a stationary coil 112 and a rotating coil
114 that is coupled radially inwardly of stationary coil 112 that
are configured to facilitate transmitting data collected from
bearing assembly 50 to a remote system such as bearing monitoring
system 200. In the exemplary embodiment, coils 104 and 114 are
coupled to a rotating component such as shaft 24 for example, and
stationary coils 102 and 112 are coupled to a stationary component
such as a turbine frame, for example. In the exemplary embodiment,
pairs of coils 100 and 110 are substantially cylindrical and extend
around an outer periphery of shaft 24. More specifically, data is
transmitted from transmitter 92 to telemetry module 94. The
information is then transmitted to rotating coil 112 such that a
corresponding electrical signal is induced in stationary coil 114.
The signal is then transmitted to bearing monitoring system 200 via
antenna 98, or alternatively is transmitted to bearing monitoring
system 200 through an antenna 120 that is channeled through the
turbine rear frame.
FIG. 6 is a cross-sectional view of telemetry system 90 in a second
operational configuration. In the exemplary embodiment, as shown in
FIG. 6, telemetry system 90 includes rotating transmitter 92 that
is electrically coupled to at least one of strain gages 72 and/or
accelerometers 73 via wiring harness 82. In the exemplary
embodiment, transmitter 92 is configured to transmit an RF signal,
for example, to a rotating telemetry module 94 that is formed
integrally with transmitter 92 is a substantially L-shaped unit
that is configured to rotate with bearing assembly 50. In the
exemplary embodiment, telemetry module 94 is coupled to transmitter
92 and is configured to supply power to transmitter 92 and to
transmit a signal received from transmitter 92 to stationary
antenna 98. More specifically, telemetry system 90 includes first
pair of induction power coils 100 that include a stationary coil
102 and a rotating coil 104 that is coupled radially outwardly of
stationary coil 102 that facilitate generating power for
transmitter 92, and telemetry module 94, and thus facilitates the
real-time collection of data from bearing assembly 50. Telemetry
system 90 also includes second pair of induction coils 110 that
include stationary coil 112 and rotating coil 114 coupled radially
outwardly of stationary coil 112 that are configured to facilitate
transmitting data collected from bearing assembly 50 to a remote
system such as bearing monitoring system 200. In the exemplary
embodiment, rotating coils 104 and 114 are coupled to a rotating
component such as shaft 24 for example, and stationary coils 102
and 112 are coupled to a stationary component such as a turbine
frame for example. In the exemplary embodiment, pairs of coils 100
and 110 are substantially cylindrical and extend around an outer
periphery of shaft 24. More specifically, data is transmitted from
transmitter 92 to telemetry module 94. The information is then
transmitted to rotating coil 114 such that a corresponding
electrical signal is induced in stationary coil 112. The signal is
then transmitted to bearing monitoring system 200 via antenna
98.
FIG. 7 is a bearing monitoring system 200 that may be used to
monitor a gas turbine engine bearing such as, but not limited to,
bearing assembly 50 (shown in FIG. 2). In the exemplary embodiment,
bearing monitoring system 200 is coupled to core gas turbine engine
10 and includes a data acquisition/control system 202 that is
coupled to bearing assembly 50 such that data collected from
bearing assembly 50 can be transmitted to/from data
acquisition/control system 202. Data acquisition/control system 202
includes a computer interface 204, a computer 206, such as a
personal computer, a memory 208, a monitor 210, and an antenna 211.
Computer 206 executes instructions stored in firmware (not shown).
Computer 206 is programmed to perform functions described herein,
and as used herein, the term computer is not limited to just those
integrated circuits referred to in the art as computers, but
broadly refers to computers, processors, microcontrollers,
microcomputers, programmable logic controllers, application
specific integrated circuits, and other programmable circuits, and
these terms are used interchangeably herein.
Memory 208 is intended to represent one or more volatile and/or
nonvolatile storage facilities not shown separately that are
familiar to those skilled in the art. Examples of such storage
facilities often used with computer 206 include solid state memory
(e.g., random access memory (RAM), read-only memory (ROM), and
flash memory), magnetic storage devices (e.g., floppy disks and
hard disks), optical storage devices (e.g., CD-ROM, CD-RW, and
DVD), and so forth. Memory 208 may be internal to or external to
computer 206. In the exemplary embodiment, data acquisition/control
system 202 also includes a recording device 212 such as, but not
limited to, a strip chart recorder, a C-scan, and an electronic
recorder, electrically coupled to at least one of computer 206 and
bearing assembly 50.
Accordingly, strain gages 72, accelerometers 73, telemetry system
90, and bearing monitoring system 200 facilitate predicting a
bearing failure. More specifically, data is continuously
transmitted from bearing assembly 50 to an antenna 214 that is
coupled to bearing monitoring system 200 utilizing telemetry system
90. The data is then analyzed utilizing an algorithm installed on
computer 206 to evaluate the current operational state of bearing
assembly 50. In the exemplary embodiment, the data is compared to
known data, i.e. a bearing performance model, to estimate a future
date in which bearing assembly 50 may possibly fail. Accordingly,
bearing assembly 50 can be repaired or replaced prior to an In
Flight Shut Down (IFSD) to facilitate avoiding an Unscheduled
Engine Removal (UER).
The telemetry system described herein can be utilized to facilitate
predicting damage to a differential bearing before significant
damage occurs. Specifically, a strain gage and/or an accelerometer
are coupled to the bearing assembly to facilitate determining
current damage to the differential bearing. Signals generated by
the strain gages and the accelerometers are then transmitted to a
remote location for further analysis utilizing the telemetry
system.
More specifically, the telemetry system described herein is
built-in to a differential bearing sump and utilizes the available
sump lube supply to facilitate maintaining the desired thermal
balance. In the exemplary embodiment, the telemetry system includes
a stationary ring and a rotating ring that are configured to
generate electrical power to various components utilized by the
telemetry system and to also transmit a signal from the installed
instrumentation to a remote location. Moreover, the inner or outer
ring can be configured to rotate depending on the specific required
design application and gas turbine engine sump configuration, such
as for example, available space within the sump, lubrication
distribution, and/or the ease of assembly and disassembly of the
telemetry system within the gas turbine engine. In the exemplary
embodiment, the rotating portion of the telemetry system is mounted
on the #5R bearing journal within the gas turbine engine, and has
the rotating transmitters secured within the air holes, and the
stationary portion of the telemetry system is integrated within the
#5R housing. Alternatively, the rotating portion of the telemetry
system is flange mounted on the aft side of the LP rotor by the
same nuts and bolts that hold the outer race flange, and the outer
differential seal on the forward side. The rotating lead wires
connecting the sensors and the transmitter are then secured within
the axial space of the bolthole to facilitate protecting the
telemetry system against the G loading. In the exemplary
embodiment, the built-in rotating transmitter provides excitation
to the sensors, and transmits sensor signals to a remote location.
Additionally, the stationary portion of the telemetry is integrated
with the stationary housing of the #5R bearing. The rotating
telemetry system described herein is configured to generate power,
and additionally to relay the sensor signals to a remote location.
The engine lube oil supply system is also used to facilitate
cooling the telemetry electronics. Specifically, the continuous oil
flow within the radial gap between the stationary and rotating
portions of the telemetry system facilitates maintaining the
desired thermal balance to safeguard the long-term survival of the
telemetry system. The power to the transmitters is maintained
either through recharging action or engine power. Finally the
sensor signals picked up by the stationary antenna are processed
through data analysis/reduction algorithms for the purpose of
bearing diagnostics, and prognostics.
The functioning of the proposed telemetry system would provide a
simplified but an improved reliable system that is built within the
sump. The thermal balance to maintain survivability is accomplished
through the already available sump lube supply. The integration of
the rotating and stationary telemetry portions with the mating sump
hardware resolves the issues related to the minimal space available
with in any differential sump. The reduced number of parts will
make the system robust and reliable. This approach will provide an
online monitoring system for production engines covering military,
commercial, and industrial applications.
The above-described telemetry system is cost-effective and highly
reliable. The telemetry system is configured to predict a bearing
failure of a differential bearing including an inner race, an outer
race, and a plurality of rolling elements positioned between the
inner and outer race. The telemetry system includes a measuring
apparatus including at least one of a strain gage and an
accelerometer coupled to the differential bearing, a cable
connected at one end to the measuring apparatus adapted for passage
through a rotating component, and a transmitter coupled to the
cable and configured to transmit a plurality of signals from the
measuring apparatus to a remote location to facilitate predicting a
failure of the differential bearing.
Exemplary embodiments of a telemetry system are described above in
detail. The telemetry system is not limited to the specific
embodiments described herein, but rather, components of the
telemetry system may be utilized independently and separately from
other components described herein. Specifically, the components of
the telemetry system may be installed on a wide variety of engines
to facilitate predicting a bearing failure within these
engines.
While the invention has been described in terms of various specific
embodiments, those skilled in the art will recognize that the
invention can be practiced with modification within the spirit and
scope of the claims.
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